Many cellular devices today are capable of processing both voice calls and internet/computer data. These devices are commonly referred to as “smartphones”. With the advent of Voice-over-IP (VoIP) technology, it has become possible to deliver voice calls over IP networks or over a combination of IP networks and the public-switched telephone network (PSTN) rather than solely over the PSTN, as was conventional.
In some systems, voice call services are provided via connection between mobile devices to an enterprise server. These systems may include a suite of call setup features and in-call features, such as those accessible to a PBX-connected desk phone. These features may be implemented by way of a signaling protocol between the mobile devices and the server. For example, a request to invoke a particular feature by a mobile device may be encoded into a signal transmitted by the mobile device to the server. Typically, signals transmitted between the mobile devices and a server are transmitted over the data channel. However, the data channel may sometimes be unavailable for various reasons.
Therefore, signals transmitted between the mobile devices and a server may be transmitted over the voice channel in DTMF. However DTMF is not a reliable and efficient data transmission mechanism in general, so there is a need for improved signaling between mobile devices and the voice mobility server.
Similar reference numerals may have been used in different figures to denote similar components.